<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>关键帧动画</title>
		<style type="text/css">
			@keyframes to_from{
				from{background-color: #7FFF00;}
				20%{height: 200px;}
				50%{background-color: #8A9AFF;width: 200px;}
				80%{height: 0px;}
				to{background-color: #7FFF00;}
			}
			@keyframes number{
				0%{}
				20%{}
				50%{}
				70%{}
				100%{}
			}
			#app{
				width: 100px;
				height: 100px;
				margin: 200px auto;
				animation: to_from 3s linear infinite 0s ;
			}
			#app:hover{
				
			}
		</style>
	</head>
	<body>
		<div id="app">
			
		</div>
	</body>
</html>
